1. Field of the Invention
The present invention relates to providing means for adjusting the geometric center of a sampling of impacts on a golf club face for a golfer toward the "sweet spot" on the club face.
2. Description of the Prior Art
Various devices for guiding the vertical position of a golf club face relative to the ground surface or grass surface have been advanced, including units which have rollers to provide reduced friction, and also clubs which have replaceable skid plates.
U.S. Pat. No. 2,057,275 shows a golf club that has a retractable spacing stand which is intended to space the bottom of the club at a predetermined distance from the ground at the beginning of a stroke. This is primarily for use on a driver. No teaching is disclosed of utilizing a runner to engage the grass or green surface prior to a stroke to provide a centering of the normal range of impact points with respect to the club sweet spot.
Sole plates have been used on golf clubs as well, and such plates are shown in U.S. Pat. No. 1,289,192. Replaceable bottom plates are shown in U.S. Pat. Nos. 2,328,583 and 2,332,342. The last mentioned two patents were issued to the same inventor, and relate to proper weighting of the golf clubs by having a removable section where weights can be added or subtracted.
U.S. Pat. Nos. 2,255,332 and 3,680,868 show roller balls on the bottom surface of golf clubs to reduce friction. These rollers are replaceable. Replacement of one type rollers with different size rollers is disclosed in U.S. Pat. No. 3,680,868.
A type of sole plate that has a raised center portion that is part cylindrical is shown in U.S. Pat. No. 2,004,968, and U.S. Pat. No. 2,090,348 shows a golf club that has flexible support fingers on the bottom surface thereof that are to space the club properly from the ground or grass surface. This is used primarily as a training device in connection with a special recording surface that will record and illustrate the direction of swing.
None of these, however, teach the use of a runner on the bottom of the club head that provides a smooth low friction surface, and which also is adjusted to insure that the most likely impact point will be close to the "sweet spot" of the club. This "most likely impact point" is the center of a number of ball-club impact points resulting from any individual golfer's natural swing. As part of the method of moving the most likely impact point toward the sweet spot, the present device also includes an adjustable aiming line. Aiming devices are known in the prior art, and for example U.S. Pat. No. 1,969,086 shows a sight point that can be adjusted to different positions between the heel and toe of a putter, but does not provide an alignment line or arm that makes it easy to hold the face of the club square relative to the plane of club swing. Other patents that show direction indicator attachments for golf clubs include U.S. Pat. Nos. 3,719,363, and 4,291,883. The latter patent shows a device that can be adjusted as to angle if desired. U.S. Pat. No. Des. 111,855 also shows a clip-on direction indicator attachment for a golf club.
None of these patents teach the adjustment of guide devices in a method that starts with establishing a normal swing pattern of a selected number of swings and recording ball impact points on the club face, and then adjusting the runner to bring the geometric center of such impact points toward the sweet spot on the face of the club.
The sweet spot on a golf club is defined generally and for purposes of this specification as point on the face (also called striking surface) where the greatest distance results from a given velocity of the club head, following impact with a ball at rest. The sweet spot is close to that point on the hitting surface which is directly ahead (or possibly behind) the center of gravity of the hitting surface, in the swing direction. It is not necessarily coincident with this point, for a variety of reasons.
Nearly all golfers "set up" a shot by first resting the club on the grass, then draw it back and make the swing. With a putter, contact with the grass is sometimes made unintentionally during the swing, and for such cases, friction against the grass is preferably minimal.